A modification of the operation for strabismus

[From the “ British Medical Journal", December 10th, I860.]

A MODIFICATION OF THE OPERATION
FOR STRABISMUS.

BY

RICHARD LIEBREICH, M.D.,

PROFESSOR OF OPHTHALMOLOGY, PARIS.

It is well known that, if the internal rectus muscle tie-'
divided in the manner now generally practised, it is
possible to correct a squint of from 2 to 21 lines in
adults, and from 21 to 8 lines in children. But, if
the deviation exceed this extent, it will be necessary
to perform two, three, or even more, successive oper-
ations.

Whilst the division of the effect between two oper-
ations, one on each eye, offers certain advantages
with regard to the symmetry and uniformity of the
movements of the eyes, the performance of a third
or fourth operation — i. e., its repetition upon a muscle
which has been already divided — is attended by great
disadvantages. In fact, by such a repetition of the
tenotomy, anything like an approximative calcula-
tion of the result is rendered impossible. In some
cases the effect will be nil, in others excessive ; so
that, as was once said by a well known ophthalmic
surgeon, when a third tenotomy has once been made,
it is impossible to predict how many more it may
be necessary to perform upon the same individual.

This is probably owing to the cicatricial adhesions
which are formed after the first operation, as they
prevent the performance of the usual simple ten-
otomy. For, if we be not careful to divide these
adhesions completely, it may easily occur that a small
band, which has escaped our notice, will mar the
effect ; or if, in order to ensure their complete divi-
sion, we have been obliged to incise the parts freely,
a divergent squint (in division of the internal rectus)
not unfrequently results, with considerable loss of
mobility inwards, sinking of the caruncle, etc. ; in

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sliort, all the disadvantages of the old and now
abandoned operation.

About a year and a half ago, I felt anxious to
remedy, if possible, these defects by an alteration in
the mode of operating; and 1 then determined to
investigate with greater accuracy : (1) the anatomical
relations of the muscles, with regard to the capsule
of Tenon, the sclerotic, conjunctiva, caruncle, etc. ;
and (2) the mechanical effect of the operation for
strabismus.

The capsule of Tenon, which encloses the whole
eyeball with the exception of the cornea, consists of
two very different portions. The posterior half, with
its smooth, firm inner surface, forms a cup in which
the eyeball moves freely, as the head of a joint in the
socket. This cup is pierced by the four recti muscles,
and forms, at the point of perforation, a sharply de-
fined ring, which enters into so close a connexion
with the muscles, as to render any displacement
between the two impossible. This close adhesion be-
tween the muscles and the posterior half of the cap-
sule is, moreover, increased by sheath-like processes,
which run backward from the outer surface of the
capsule towards the orbit, and which are, for a cer-
tain distance, firmly connected with the muscles.
But, towards the eyeball, no sheath-like processes
extend from the posterior capsule; the latter ter-
minates abruptly in the form of a ring, which en-
closes the spot where the muscles penetrate, and
whence, for a very short distance, the muscles are
quite free from any adhesion. But before the tendon
is inserted into the sclerotic, it penetrates between
the sclerotic and the anterior half of the capsule, and
becomes united with the latter.

This anterior half of the capsule, which may be
considered as standing towards the posterior por-
tion in the relation of a semicircular lid to a semi-
circular cup, is much thinner than it, and is difficult
to dissect, more especially on the dead body ; for, like
the conjunctiva, it rapidly diminishes in thickness
and firmness after death.

If we trace the anterior half of the capsule from
the anterior pole of the eye towards the periphery,
we commence with a circular opening which corre-
sponds to the size of the cornea, and through which
the latter projects. The margin of this opening is

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in close apposition to the sclerotic. Within a zone,
which is bounded on one side by the opening on the
margin of the cornea, and on the other by the line
uniting the insertion of the four recti muscles, the
conjunctiva, the capsule of Tenon, and the sclerotic,
are firmly and immoveably connected together. At
the periphery of the zone, this condition becomes,
however, changed. The connection between the cap-
sule and the sclerotic is interrupted by the passage
of the muscles. The lax cellular tissue, which here
connects the sclerotic with the capsule and the inner
surface of the muscle, may perhaps have given rise to
such complex and fanciful descriptions as those of
Guerin. ( Gazette Medicale, 1842, No. 6.) The idea
that the muscles, after they have pierced the cap-
sule, are accompanied as far as their insertion by
sheath -like processes derived from it, has, owing to
these descriptions, maintained itself in ophthalm-
ology even up to this time, and has served as a basis
for explanations of the effect of the tenotomy, the
difference between the old and modern mode of oper-
ating, etc. This idea is, however, erroneous ; for
these sheath-like processes do not exist at all. But,
as has been already mentioned, the anterior half of
the capsule of Tenon certainly adheres to the upper
surface of the muscle and is intimately connected
with it. On the other hand, the conjunctiva is here
also tolerably firmly connected with the capsule, as
far as a somewhat irregularly circular line, which
may be recognised by the fact that it lies at the
bottom of a furrow when the eye is moved in an ex-
centric direction. The formation of this furrow pre-
vents the sinking and tilting forwards of the con-
junctiva, which would otherwise occur near the
caruncle, as, for instance, when the eye looks far in-
wards. From this marginal line, the connexion be-
tween the capsule of Tenon and the conjunctiva be-
comes quite lax. One portion of the connective
tissue, which composes the anterior half of the cap-
sule, is reflected, and passes over into the submucous
tissue of the eyelids ; another portion attaches itself
to the edge of the posterior half of the capsule, in
order thus to close the latter. These two halves do
not really pass perfectly over into one another,
inasmuch as the edge of the posterior half of the
capsule is partly continued into the band-like adhe-

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sions between it and the edge of the orbit. From
this description, we must call special attention to
three points, as being particularly important with
regard to the performance of the operation for stra-
bismus.

1. The connection of the muscle with the capsule
of Tenon is two-fold. On the one hand, there is the
annular connection of the posterior capsule and its
sheath-like processes (which are reflected towards the
orbit) with the belly of the muscle ; on the other, the
firm adhesion of the anterior half of the capsule to
the surface of the end of the muscle, which penetrates
into the capsule.

2. The conjunctiva is firmly connected with the
outer surface of the capsule of Tenon, from the edge
of the cornea to an irregularly circular, sharply de-
fined, marginal line ; and, consequently, it stands in
a very important relation to the muscles of the eye.

3. The caruncle, together with the semilunar flap,
rest upon a band-like ligament, which passes from
the capsule of Tenon towards the edge of the orbit.
Now, when the internal rectus is contracted, and the
eye rolled inwards, this band is rendered tense ; and
the caruncle, which is fixed to it, is consequently
drawn in towards the inner edge of the orbit. But
the outer edge of the caruncle, together with the
semilunar fold and an adjoining portion of conjunc-
tiva, are drawn backwards into a furrow. This is
partly due to the fact that, during the movements of
the eye, the conjunctiva lies, up to a certain point,
in close apposition to the eyeball; and partly also to
the fact that, on contraction, when the muscle, on
account of its connection with the anterior half of the
capsule, must draw the latter backwards, where it
will be followed by the conjunctiva (which is likewise
connected with the capsule), the semilunar fold, and
the caruncle.

From a consideration of the first of these three
points, we learn with regard to the mechanical effect
of the operation for strabismus, that a division of the
insertion of a muscle can only be brought about by a
division of the portion of anterior capsule which
covers the muscle. For this portion, which passes
over the muscle to become attached to the sclerotic
just before the insertion of the tendon, keeps the
muscle in a fixed position with rogard to the scle-

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rotic ; so that, it we attempt to sever the tendon
from the sclerotic without dividing this portion of
the capsule, the tendon would become reunited ex-
actly at its original point of insertion; so that, in
fact, it would not have receded at all. It would,
however, be not only very difficult, but almost im-
possible, to avoid incising this portion of the cap-
sule, as, on account of its intimate adherence to the
insertion of the muscle, it is always divided simulta-
neously with it. Even in the subconjunctival opera-
tion, although the conjunctiva which covers this
portion of the capsule is left intact, the capsule itself
is divided along the whole breadth of the insertion
of the muscle. This vertical incision of the capsule
of Tenon, which always takes place simultaneously
with the tenotomy, is the cause of the retrocession of
the anterior part of the capsule covering the muscle,
and of the annular portion of the capsule which
beeps the muscle fixed, and consequently, also, the
retrocession of the muscle itself. By increasing the
length of the incision in the capsule (Graefe’s divi-
sion of the lateral processes), we may certainly pro-
duce a somewhat greater retrocession ; but, owing to
the second point mentioned above, it cannot be very
extensive. Eor the connexion of the conjunctiva
with the capsule does not permit a more considerable
retrocession of the latter, unless we make an exten-
sive vertical incision in the conjunctiva, analogous
to that in the capsule, and thus jointly divide the
conjunctiva, capsule, and tendon. Such a proceeding
is, however, accompanied by considerable disadvan-
tages. On account of the connexion between the
muscle, capsule, and caruncle, the divided muscle
draws the caruncle and the semilunar fold back-
wards and inwards, as well as that portion of the
conjunctiva which was divided by the vertical inci-
sion. In consequence of this, these parts assume
the same position when the eye looks straight for-
ward, which they do in the normal eye when it is
turned very far inwards. At the same time, the dis-
tance between the semilunar fold and the inner
edge of the cornea is increased, as also the portion
of sclerotic visible at the inner angle of the eye ; and
this gives to the eye that peculiarly disagreeable
appearance which was so characteristic of the old
operation.

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In order to obviate these disadvantages, and yet
obtain a much more considerable effect, I am
in the habit of performing the following modifi-
cation of the operation for strabismus, which is based
upon the above considerations.

If the internal rectus is to be divided, I raise
with a pair of forceps a fold of conjunctiva at
the lower edge of the insertion of the muscle ;
and, incising this with scissors, enter the points
of the latter at the opening between the conjunc-
tiva and the capsule of Tenon ; then carefully sepa-
rate these two tissues from each other as far as
the semilunar fold, also separating the latter,
as well as the caruncle, from the parts lying behind.
When the portion of the capsule which is of such
importance in the tenotomy has been completely
separated from the conjunctiva, I divide the inser-
tion of the tendon from the sclerotic in the usual
manner, and extend the vertical cut, which is made
simultaneously with the tenotomy, upwards and
downwards — the more so if a very considerable effect
is desired. The wound in the conjunctiva is then
closed with a suture.

The same mode of operating is pursued in dividing
the external rectus ; and the separation of the con-
junctiva is to be continued as far as that portion of
the external angle which is drawn sharply back when
the eye is turned outwards.

The following are the advantages of my pro-
ceeding.

1. It affords the operator a greater scope in appor-
tioning and dividing the effect of the operation be-
tween the two eyes.

2. The sinking back of the caruncle is avoided, as
well as every trace of a cicatrix, which not unfre-
quently occurs in the common tenotomy.

3. There is no need for more than two operations
on the same individual, and therefore of more than
one on the same eye.

With regard to point 1, we may, if we choose, pro-
duce either the effect of the common tenotomy, or
we may correct a deviation of four lines or even
more in adults, and of five lines or more in children.
In order to prevent the repetition of misunderstand-
ings which have arisen from my viv& voce statements,
I would remark, that it is by no means my intention.

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when the squint is so considerable in degree (four
lines in adults, five lines in children), to perform in
all cases only one operation. Indeed, in such cases,
I entirely agree with the principles laid down by
Yon Graefe ;viz., to divide the effect of the operation
between the two eyes. It is only in exceptional
cases, in which the mobility inwards of the squinting
eye is much increased, and the aperture between the
lids is not wider than in the other eye, that I correct
so considerable a deviation by one operation. If
certain personal considerations — as, for instance, the
departure of the patient — render a repetition of the
operation impossible, I prefer a single modified teno-
tomy to the proceeding adopted by other surgeons
(e. g., at Moorfields Hospital), viz., the simultaneous
division of both internal recti muscles. If the devia-
tion amounts to three lines in adults, or four lines in
children, I generally perform only one tenotomy. It
is probably chiefly owing to the possibility of curing
a squint of this extent by a single operation, and
without any sinking of the caruncle, that the preju-
dice against the operation for strabismus, which I
encountered, not only amongst the public, but even
in the medical profession, when I first settled in
Paris, has now nearly entirely disappeared. So I
am able, by this mode of operating, to correct the
deviation in those cases in which the patient, owing
to this prejudice, would never have consented to an
operation upon both eyes.

With regard to point 2, I need only mention that
the suture is to be applied in all cases. I think it of
consequence that the conjunctival wound should be
completely closed, and in such a manner that the
conjunctiva reassumes its original position, so that
the edges of the wound cannot become shifted from
each other. If the finest English black silk and fine
curved needles be used, no disadvantages can accrue,
even if it should be necessary to apply several su-
tures.

But I consider the third point — the avoidance of
more than two operations upon the same individual
—as the most important. I hope that all surgeons
who agree with me as to the disadvantages of a third
or fourth tenotomy, will adopt my mode of operating
in all cases of very considerable strabismus. The
permanent effect must not, however, be estimated

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according to the immediate, but the ultimate, result ;
for the difference between these two is far greater in
the modified operation (more especially if it be done
extensively) than in the common one ; and this
applies not only to the deviation, but also to the loss
of mobility. We find more especially that the loss of
mobility, which is very considerable immediately
after the operation, subsequently diminishes more
and more, until it finally does not in the least exceed
that which follows the common operation.

T. RICHARDS, 37, GREAT QUEEN STREET.